Presentation Abstract

Within the marine-terrestrial ecotone, upper intertidal “wrack zones” accumulate organic debris from algae, seagrass, and terrestrial plant sources and provide food and shelter for many organisms. We conducted detailed surveys of wrack and log accumulations and supralittoral invertebrates in spring and fall over 3 years at 29 armored-unarmored beach pairs in Puget Sound, WA, USA. Additionally, behavioral observations of juvenile salmon (Oncorhynchus spp.) and birds were conducted at 6 pairs. Armored beaches had substantially less wrack overall, a lower proportion of terrestrial plant material in the wrack, and far fewer logs. Armored beaches had significantly fewer invertebrates and differed from unarmored beaches in their taxonomic composition. Unarmored invertebrate assemblages were dominated by talitrid amphipods and insects, and were correlated with the amount of beach wrack and logs, the proportion of terrestrial material in wrack, and the maximum elevation of the beach. Shoreline armoring influenced juvenile salmon distribution, with fewer overall observations and fish in deeper water at armored beaches, but their feeding rates were relatively high at all sites. Terrestrial birds were commonly observed foraging among beach wrack and logs at unarmored beaches, but were largely absent from armored beaches. This study demonstrates that shoreline armoring disrupts marine-terrestrial connectivity, affecting the amount and type of organic material delivered to the nearshore ecotone in the form of wrack and logs, the abundance and taxonomic composition of supralittoral invertebrates, and the distribution and behavior of secondary consumers (juvenile salmon and birds).

Session Title

Session S-06H: Puget Sound Shorelines and the Impacts of Armoring: State of the Science 2014

Conference Track

Shorelines

Conference Name

Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)

Document Type

Event

Start Date

1-5-2014 1:30 PM

End Date

1-5-2014 3:00 PM

Location

Room 607

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

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This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

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May 1st, 1:30 PMMay 1st, 3:00 PM

Shoreline armoring disrupts marine-terrestrial connectivity in the Salish Sea, with consequences for invertebrates, fish, and birds

Room 607

Within the marine-terrestrial ecotone, upper intertidal “wrack zones” accumulate organic debris from algae, seagrass, and terrestrial plant sources and provide food and shelter for many organisms. We conducted detailed surveys of wrack and log accumulations and supralittoral invertebrates in spring and fall over 3 years at 29 armored-unarmored beach pairs in Puget Sound, WA, USA. Additionally, behavioral observations of juvenile salmon (Oncorhynchus spp.) and birds were conducted at 6 pairs. Armored beaches had substantially less wrack overall, a lower proportion of terrestrial plant material in the wrack, and far fewer logs. Armored beaches had significantly fewer invertebrates and differed from unarmored beaches in their taxonomic composition. Unarmored invertebrate assemblages were dominated by talitrid amphipods and insects, and were correlated with the amount of beach wrack and logs, the proportion of terrestrial material in wrack, and the maximum elevation of the beach. Shoreline armoring influenced juvenile salmon distribution, with fewer overall observations and fish in deeper water at armored beaches, but their feeding rates were relatively high at all sites. Terrestrial birds were commonly observed foraging among beach wrack and logs at unarmored beaches, but were largely absent from armored beaches. This study demonstrates that shoreline armoring disrupts marine-terrestrial connectivity, affecting the amount and type of organic material delivered to the nearshore ecotone in the form of wrack and logs, the abundance and taxonomic composition of supralittoral invertebrates, and the distribution and behavior of secondary consumers (juvenile salmon and birds).